Muffler



MUFFLER G. A.. KINGSLEY Filed April 5, 1935 Patented Aug. 2, 1938 UNlTEDSTATES PATENT GFFHCE MUFFLER Application April 5, 1935, Serial No.14,850

S Claims.

The present invention relates to improvement in muliler structure forinternal combustion engines and having particular reference to mufers ofthe general type illustrated by U. S. Patent No. 1,931,736 to Noblitt etal.

In mufrlers of the above -mentioned type to obtain compactness ofstructure the gases are passed back and forth through the muiiler casingbetween the inlet and discharge openings.

lo The design of the muier is such that the gases have a relatively freepassage through the muffler casing avoiding the creation ofobjectionable back pressure yet at the same time the muffler ischaracterized by its silencing efficiency.

l5 It is an object of the invention to simplify and thus reduce the costof manufacture of the above type of muflier and at the same time ennhance the silencing efficiency thereof.

Another object is to provide a mufier which 30 is strong and durable andparticularly designed.

to resist destruction by backfire.

A still further object is to produce a muffler n which decelerationnoises are avoided as well as high pitch noises or whistling at time of:l5 high gas velocity.

in the specific embodiment shown in the above mentioned patent threeseparate tubes are provided in the muffler casing for a. triple passageof 'the gases. According to the present inven- :30 tion a triple passageof the gases through the casing is possible With a pair of tubes; themufiier casing acting as a conduit for the gases from one end of themuilier casing to the other and for interconnecting such tubes. in thepre- ;35 ferred form, these main tubes, through which the main ficw ofgases pass, are each concentrically supported within intermediate tubeswhich define a chamber about each tube separating the same from themuliler casing. These chambers Ll0 are divided up by partitions intoseparate chambers arranged longitudinally of each tube. The main tubesare perforated to effect communication with the chamber surrounding thesame. In

F the silencing of the exhaust gases of certain engines perforations mayalso be advantageously provided in the intermediate tubes to effect adiffusion or short circuiting of the gases into the conduit defined bythe muflier casing.

In the accompanying drawing wherein two forms of the invention areillustrated,

Fig. l is a cross-sectional view through the muffler casing,

Fig. 2 is a cross-sectional view taken on line 55 II--I of Fig. l, and

Fig. 3 is a view similar to Fig. 2 of a modified form of the invention.

In the mufller illustrated in Figs. l. and 2, the cylindrical outercasing l is closed at opposite ends by headers l2 and Mi having inletand discharge openings it and i8, respectively. Tubes 2o and 22constituting main conduits for the flow of gases between the inlet andoutlet openings are concentrically supported within intermediate tubesEri and 2t by baffle members 2B. These pairs of concentricallyassociated tubes are located in overlapping relation within the casingiii to provide chambers 3@ and 32 communicating with longitudinallyextending chambers 34 and 36 dened within the casing lil. The tube isshown communicating with the inlet it through a conical connector Si.

The tubes 2li and 22 are shown as perforated to effect communicationwith the chambers it@ which act as acoustic wave filters or resonator ina manner well known. Preferably the perforations in the tubes 2t and 'Z2take the form of angularly disposed elongatedslots l2 as such aconfiguration has been found to eliminate the creation of high pitchnoises or whistling in the muffler due to the passage of the gasesacross the same, all as fully discussed and treated in my copendingapplication Serial No. 14,848, 1filed April 5, i935. These chambers fi@may be closed in some instances and in others it has been foundadvantageous to perforate the same in some suitable manner such as withslots it which permits a diffusion or short circuit of a portion of thegas ow out of the intermediate tubes 2li and 2t into the chambers 35iand 3K5 or from the intermediate tube 24 through the chambers 3Q and 3'3into the intermediate tube it and hence into the tube 22 into thedischarge dow. The size and number of perforations in the chambers filmay be varied at will to regulate the back pressure in the muliler. Alsothis diffusion of the gas iow between the intermediate tubes is ofassistance in noise suppression as the sound waves from the inlet anddischarge tubes 2G and 22 meet and cancel cach other.

It is to be noted that the connection @el is shown as provided withperforations it similar to those in the tubes 2Q and E2 permitting aportion of the gases to flow into the chamber l-S and hence into thechambers and through perforations i9. By regulating the 'perforate areain the connection 38 the same muler structure is adaptable to differentengines with controlled back pressure. Obviously by short circuiting aportion of the gas flow the diameter of the inlet tube 20 can besubstantially less in diameter than the exhaust pipe leading to themuffler Without building up back pressure. Thus the chambers 40surrounding the tube 2U are of maximum volume which enhances the noisesuppression properties of the same and makes it possible to reduce thediameter of the casing l0 to a minimum.

At the present time it is my theory that the angularly disposed slots 42impart a whirling action to the gases flowing along the inlet anddischarge tubes 20 and 22 and that a similar action is imparted to thegases filling and passing through the chambers 4B. This whirling actionof the gases is thought to be at least in part responsible for theimproved sound suppression characteristic of my improved muffler.Another important feature of the present invention contributing to thesilencing effectiveness of the invention resides in the double wall madeup of the casing IU and the intermediate tubes 24 and 26 as at 50 and 52in Fig. 2. IThis prevents or decreases so called shell noise. A furthersilencing feature resides in having a large chamber made up of thechambers 36, 32, 34 and 36 between the inlet and discharge tubes makinga balanced circuit. This large chamber as located acts to obviatedeceleration noises instead of agitating the same as in the usual casewith a chamber in a circut, especially in the more restricted type ofmuier. This large chamber acts as a conducting passage between the inletand discharge tubes 2i] and 22 opening into and leading from thechambers 32 and 3G, respectively. It also acts to expand and cool thegases and as a general diffusion chamber when the chambers 40 areperforated.

In the modified embodiment of the invention shown in Fig. 3, the outercasing 55 is oblong with semi-cylindrical portions 56 and 59 whichtogether wih longitudinal split tubes B and 52 define tubescorresponding to the intermediate tubes 24 and 2E. Inlet and dischargetubes 64 and 66 are concentrically supported within the semi-cylindricalportions 56 and 52S. The arrangement of these tubes may be the same asin the structure shown in Fig. 1 with opposite ends thereofcommunicating with the chambers 68 and 10 corresponding to the chambers34 and 36. The structure shown in Fig. 3 has the advantage that theouter casing defines in part the intermediate tubes and permits the useof two half tubes in lieu of two whole tubes as in the structure shownin Figs. l and 2.

As many changes may be found necessary in the muffler structure shownand disclosed to meet particular engine requirements Without departingfrom the scope of the invention, it is intended that all mattei'contained in the above description shall be interpreted as illustrativeand not in a limiting sense. For the most part these changes will beconfined to variations in proportions of parts, the perforations andconfiguration of the conductors for the gases, and the position of theassociated tubes relative to each other. For example, the tubes 2B and22 need not be concentrically located Within the tubes 24 and 26.Installation of the muffler may require that such tubes be eccentricallyassociated. Other changes will readily occur to those skilled in theart.

Having described my invention what I desire to protect by Letters Patentand claim is:

l. A muflier comprising a casing having inlet and discharge openings atopposite ends thereof,

an inlet conduit for conducting gases from one end of said casing anddischarging the same into the interior of the casing at the opposite endthereof, a second conduit for conducting gases from the interior of saidcasing at the inlet end of the same to said discharge opening, and meansrestricting the flow of gas adjacent the inlet end, said first conduithaving means for short circuiting a portion of the gas fiow therethroughinto the interior of said casing adjacent the inlet end.

2. A muffler comprising a casing having lnlet and discharge openings,inlet and discharge tubes communicating with said openings, said tubesbeing located in said casing in offset relation and constitutingconduits ior the free passage of exhaust gases from one end oi' saidcasing to the other, said tubes at opposite ends of said casing openinginto the interior thereof, and an expansion chamber through whichcommunication is established between said tubes, said inlet tube beingof less cross-sectional area than said inlet opening, said inlet tubehaving means for short circuiting a portion of the gas flow therethroughinto the interior of said casing adjacent the inlet end.

3. A muiiier comprising an elongated cylindrical outer casing closed atboth ends except for inlet and discharge openings, inlet and dischargecylindrical tubes located within said casing and communicating with saidopenings, said tubes being disposed in offset relation and extendingthroughout substantially the length of said casing affording anunobstructive free passage of the gases therethrough, intermediatecylindrical tubes Within which said first tubes are supported anddefining a chamber therewith, said intermediate tubes having an insidediameter of approximately one-half the diameter of said outer casingwhereby said intermediate tubes are closely fitted thereto to provide adouble wall structure for said first tubes, said first tubes beingperforated along their length and at opposite ends opening into oppcsiteends of the interior of said casing.

4. A mufiier comprising an elongated casing having inlet and dischargeopenings at opposite ends, inlet and discharge tubes in offset rclationcommunicating with said openings and defining free passageways for thefiow of gases longitudinally of said casing, intermediate tubes Withinwhich said first tubes are supported to define chambers, perforations insaid first tubes communicating with said chambers, said first tubesopening into the interior of said casing at opposite ends thereof, saidcasing and intermediate tubes defining an expansion chamber for thegases and a conduit through which communication is effected between saidfirst tubes.

5. A muffler comprising an elongated casing having inlet and dischargeopenings at opposite ends thereof, means defining passageways for thefree flow of gases back and forth longitudinally of said casing betweensaid openings, and means located adjacent said inlet opening forrestricting the fiow of gases passing toward said passageways, saidpassageways having means for short circuiting a portion of therestricted gases from one to another thereof.

6. A multiple muiiier comprising an elongated casing having inlet anddischarge openings at opposite ends thereof, offset means definingpassageways for the free ow of gases from and toward said openings, anexpansion chamber and passageway defined by said means and casingcommunicating with said means through which the gases flow in acounter-direction to the flow in said means, and means defining apassage adjacent said inlet opening for short circuiting a portion ofthe flow of gases.

'7. A multiple gas muffler comprising an outer casing, inlet anddischarge headers therefor, means with said headers defining chambers atopposite ends of said casing, a perforated inlet tube for conductinggases longitudinally of said casing and opening into one of saidchambers, a perforated discharge tube for conducting gaseslongitudinally of said casing leading from the other of said chambers,means defining a series of longitudinally arranged resonance chamberswith each of said tubes, said last means and casing defining anelongated chamber constituting a return between said first chambers.

8. A multiple gas muffler comprising an outer casing, inlet anddischarge headers therefor, means with said headers defining chambers atopposite ends of said casing, a perforated inlet tube for conductinggases longitudinally of said casing and opening into one of saidchambers, a perforated discharge tube for conducting gaseslongitudinally of said casing leading from the other of said chambers,and means defining a series of longitudinally arranged resonancechambers Within each of said tubes, said last means and casing definingan elongated chamber constituting a return between said first chambers.

GEORGE A. KINGSLEY.

